/*
 * @lc app=leetcode.cn id=104 lang=javascript
 *
 * [104] 二叉树的最大深度
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var maxDepth = function(root) {
  let queque = []
  if (root === null) {
    return 0
  }
  queque.push(root)
  let depth = 0
  while (queque.length ) {
    let n=queque.length
    depth++
    for (let i = 0; i < n;i++){
      let node = queque.shift()
      node.left&&queque.push(node.left)
      node.right&&queque.push(node.right)
    }
  }
  return depth
};
// @lc code=end

